Evaluation of the performance of a whole-body positron imaging system with attenuation correction.

A PET scanner with ring detectors has been modified to accomplish whole-body imaging with attenuation correction. To evaluate the performance of this system, phantom studies and clinical studies were performed in seven patients. The transaxial resolution (FWHM) at the center of the field was 8.6 mm, and the axial resolution was 12.3 mm. The counts on the images with attenuation correction were linearly related to accumulation of the radiopharmaceuticals, and attenuation correction was made accurately. The transmission scan from the top of the head to the thigh, about 110 cm in length, required 36 minutes, and one emission scan required 18 minutes. The total study time for one transmission scan and three sequential emission scans was 1.9 hours. In clinical studies, attenuation correction made the discrimination of organs clearer, and would facilitate the detection of tumors, especially those in the high attenuation organs or matter. The use of this system made it possible to obtain quantitative whole-body positron images with adequate diagnostic quality within a reasonable scanning time.